Could use some help with my Geosesarma Bicolor, please!

[hmarjolijn]

Hello everyone,

I'm having a few problems with my Geosesarma Bicolor. One by one they're slowly dying and I can't seem to understand why. Since they're my first crabs I hoping I did everything right so far, but could use some input from more experienced people.

I bought my first 5 Geosesarma Bicolors the first weekend of December last year. Two male, 3 female, about 2,5 cm big. One of the females died the next day, which was sad, but I figured that was due stress of traveling (she was pregnant aswell).

I set them up in my tank (60x60x56), which is an old aquarium from my dad. The soil is plantation soil from exoterra with frog moss on top. I put in some plants, all clean, and some wood to create hidingspots.
Underneat is a heating pad that warms the terrarium during the day. It also creates a warm spot and a cool spot to sit. Daytime warmspot is 27C, the coolspot 24C. At night temperture drops to 23C at the warmspot and 20C at the coldspot. Air temperature is the same as the coldspot temperature. The water doesn't heat up or cool down as quick so is about 22-23C al the time. Humidity is around 80% all day.

I feed my crabs mostly living foods; mosquito larvies, fruitflies and Daphnia. I also feed frozen Daphnia and krill. They also got some fishflakes, but they never ate any of it.

They seemed to be very happy, eating very well, but Chrismas day one of the females sat in the waterbowl for hours. I figured she was molting, but nothing happend and the next day she died in the waterbowl.

The others seemed fine so I didn't worry yet. The last female molded succesfully about 2 weeks later. And I carried on doing what I did.

Then in the beginning of February my big male died. I found him one morning, next to the waterbowl. He seemed ok the day before. Since I started to worry now, I reread some articles about my crabs and decided to feed the last two some extra Calcium. I didn't do that before, since the man I bought them from said the didn't need it. So I dusted my fruitflies before feeding and added some powder on the wood in the terrarium so they could eat some extra.

Last week I found my last male dead in the tank, again with no obvious reason why he died. So I'm left with my last female (the only one that did molt).

Again I hit the articles to research anything I missed, but I can't figure it out.
I did read something about adding iodine to the water, but I can't find it anymore. Does anyone here uses it?
I also can't find anything about UV light, do they need it? Because that could be a missing point then.

How often should they molt? I've got the feeling they just need to mold, but can't get it done and die. Am I missing something in the diet then, or is it set up related?
Any help is welcome, I don't want to buy another pair untill I'm sure I'm actually doing it right....

Photo's of my set up (not very good, since I made them with my phone, but you'll get the idea):





The tank is 60x60x58. The waterbowl is 12cm across and 3 cm deep.

[Ollie Mengedoht]

Hi and welcome hmarjolijn!

Well, many things seem to be good, as for example the size of the tank. Let's see what we can find out.

2,5 cm the carapace only or including legs? If You mean the width of the shell alone they were very old already.

With commercial moss our experience is very very bad with crabs. There were several times total losses of crab populations in private tanks after adding bought moss – never with moss out of nature (but there are protected species which You may not collect in Your country). Probably the commercial moss is decontaminated – and the copper in the agent kills nearly all invertebrates including crabs. So maybe You would want to change that moss against moss You collected in the free, far from big streets, industry AND agriculture (regarding farming and fertilizers the same applies as with decontamination, fertilizer mostly contain deadly copper).

The heating pad should be at the back or sides of a tank, not underneath it. Cause: Crabs dig burrows to escape high temperatures. If hey dig in the tank and get nearer to the heat pad it gets warmer – no good. Although in that short time that shouldn'T have done anything with Your crabs! Just an advice for the future. Temperatures else seem to be good.

The water bowl should be quite bigger if possible. G. bicolor (it isn't bicolor by the way but we didn't publish that anywhere yet) needs a real water part which should be filtered in the first months after setting up at least.

Calcium should be available in the tank at all times.

UV or other light is not needed as far as we know it, no.

Molting happens every few days in younglings and up to once a year or so in adults.

So transportation stress might be a cause for dying, maybe simple the age… Temperature, humidity, feeding seems well. You might bring a bit more structure into Your setup but too that is nothing that caused problems yet – You can work with cork for example and make terraces in the tank. If You build in a bigger water part please think of several (!) possibilities to climb in and out for the animals. Else one "boss" might block the entrance for all others.

That's no definitive reason for Your problems yet but maybe we came a little nearer to a solution.

[hmarjolijn]

Thank you for your quick answer, BEASTIEPENDENT!

I remeasured my crab (I kept the biggest male after he died) and his carapace is 2 cm, the females are just a bit smaller. So if I understand it correctly they are a bit older already and should mold maybe once or twice a year?

I bought the moss from a dartfrog keeper/breeder and it was full of flying insects when I got it. Frogs don't do very well with treated moss, so I thought it should do for crabs aswell.

I can still remove the heating pad from underneat and put it on the side. So that is a quick fix, just have to find out how to make it look pretty (which is not important for the crabs )

I already bought cuttlebone this morning and put it close to my last crabs hiding space. If I eventually get some more crabs, do I need to put close to all hidingplaces or will they actively seek it out? Do I need several places or is one 'cental' place enough? Should the water have a lot of calcium too? Our tapwater is around 13 dH.

Furthermore I'm thinking about the new waterfeature. I still need to buy some stuff, but then I can change it this weekend and include some more stucture. I'm not very good in German, but trying to read some extra's on this forum, I understand it would be best to have about 1/3 of my tank water about 8 cm deep with multiple exits. Do the need hiding space in the water aswell?

Then one last question about the skin after molting. Do you leave it in your tank? In the water or on land?

Thank you again for helping the newbie, I really appreciate it!

Oh, how is G. Bicolor named now?

[Ollie Mengedoht]

So if I understand it correctly they are a bit older already and should mold maybe once or twice a year?

yep

…Frogs don't do very well with treated moss, so I thought it should do for crabs aswell.

That should be okay then.

If I eventually get some more crabs, do I need to put close to all hidingplaces or will they actively seek it out?

Better do so – Geosesarma are quite faithful to a habitat.

I'm not very good in German, but trying to read some extra's on this forum, I understand it would be best to have about 1/3 of my tank water about 8 cm deep with multiple exits.

Outch, look here: http://www.panzerwelten.de/forum/thread-711.html That species databasse is suitable for Geosesarma so. "Vampire" as for the sp. "red" and the "bicolor" too. Yes, one third is a common and usable suggestion.

Do the need hiding space in the water aswell?

Please.

Then one last question about the skin after molting. Do you leave it in your tank? In the water or on land?

You can leave it in, some (!) crabs use it and eat it for the minerals and calcium inside it. But You can take it out also to prepare and keep it. They have enough minerals and calcium in the tank with Your feeding.

Thank you again for helping the newbie, I really appreciate it!

Youre welcome – that's what this board is made for.

Oh, how is G. Bicolor named now?

Not at all. It's in the process of being described right now by friends of ours. When they have a new name we will tell it "everywhere" of course, but now no one knows yet.

[hmarjolijn]

Thanks you for all answers. I'll use your tips tomorrow to fix up my tank.

Just one last question. My friend bought some G. tiomanicum last month and has a similiar set up. I can find a caresheet for them, which one would fit best? Do they also need a big pool?

[Ollie Mengedoht]

Yes, indeed they do.

But please do never mix different Geosesarma species in one tank. Our experience is one species feeds on the other.

[chaohuang]

Yes, indeed they do.

But please do never mix different Geosesarma species in one tank. Our experience is one species feeds on the other.

I keep different species together because I lack the space. They seem to do fine, it seems to be more of a matter of density. If it is too crowded, they will eat each other, even of the same species.